import java.sql.Array;
import java.util.ArrayList;
import java.util.LinkedList;

/**
 * <p>给定一个不含重复数字的数组 <code>nums</code> ，返回其 <em>所有可能的全排列</em> 。你可以 <strong>按任意顺序</strong> 返回答案。</p>
 *
 * <p>&nbsp;</p>
 *
 * <p><strong>示例 1：</strong></p>
 *
 * <pre>
 * <strong>输入：</strong>nums = [1,2,3]
 * <strong>输出：</strong>[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]
 * </pre>
 *
 * <p><strong>示例 2：</strong></p>
 *
 * <pre>
 * <strong>输入：</strong>nums = [0,1]
 * <strong>输出：</strong>[[0,1],[1,0]]
 * </pre>
 *
 * <p><strong>示例 3：</strong></p>
 *
 * <pre>
 * <strong>输入：</strong>nums = [1]
 * <strong>输出：</strong>[[1]]
 * </pre>
 *
 * <p>&nbsp;</p>
 *
 * <p><strong>提示：</strong></p>
 *
 * <ul>
 * <li><code>1 &lt;= nums.length &lt;= 6</code></li>
 * <li><code>-10 &lt;= nums[i] &lt;= 10</code></li>
 * <li><code>nums</code> 中的所有整数 <strong>互不相同</strong></li>
 * </ul>
 *
 * <div><div>Related Topics</div><div><li>数组</li><li>回溯</li></div></div><br><div><li>👍 3080</li><li>👎 0</li></div>
 */

//leetcode submit region begin(Prohibit modification and deletion)
class Solution {
    List<List<Integer>> res = new ArrayList<>();
    LinkedList<Integer> path = new LinkedList<>();


    public List<List<Integer>> permute(int[] nums) {
        backtracking(nums);
        return res;
    }

    private void backtracking(int[] nums) {
        if (path.size() == nums.length) {
            res.add(new ArrayList<>(path));
            return;
        }
        for (int i = 0; i < nums.length; i++) {
            if (path.contains(nums[i]))
                continue;
            path.add(nums[i]);
            backtracking(nums);
            path.removeLast();
        }
    }
}
//leetcode submit region end(Prohibit modification and deletion)
